# The EM Wave Spectrum

## How are EM waves and mechanical waves different?

Electromagnetic waves are different from mechanical waves in two ways. One way is that there are two parts to EM waves, electric and magnetic. Another way that these waves are different is that em waves are able to travel through vacuums.

## What kind of disturbance creates an EM wave?

Vibrations in electric and magentic feilds
The Electromagnetic Spectrum

These waves have the lowest frequency and longest wavelength in the electromagnetic spectrum. Some radio waves are longer than our planet. They are used for television signals and AM radio. Since these are the longest waves, they have the lowest energy and temperature.

## Microwaves

These waves are used for cooking food in just a few minutes, and they allow astronomers to learn about the structure of nearby galaxies. Microwaves have near to the least energy, and also near to the lowest frequency. It's frequency is 1.6-30 GHz. It's wavelength, however, is one of the longest in the EM spectrum that spans anywhere from 1mm to 1 m.

## Infared

Infared wavelengths tend to be between 710 nm to 1 mm. It's got more energy than microwaves at 900 Newton meters. The frequency of infared is 300 GHz. Night vision goggles use infared to pick up on the light that our skin and other objects emit. Also, in space, infared light helps us map the dust in between stars.

## Visible Light

Visible light wavelengths are from 400 nm to 700 nm. The frequency is 4 x 10 ^14 Hz. It has more energy than infared but less than gamma. These waves are used for anything from seeing rainbows, cars move by, or watching television. Whenever you see something, you're using visible light.

## Ultra-violet

Ultra-violet light has a wavelength from 10-310 nm. It almost has the most energy in the EM spectrum, and it's frequency is 7.5 x 10 ^14 Hz. UV light is why we tan and burn. All objects that are "hot" in space radiate UV light.

## X-Rays

X rays range in wavelength from .01 to 10 nm. Dentists use x-rays to image your teeth, and airport security officers use them to see through your bag. X-rays have almost the highest energy, and have a frequency of 3 x 10 ^16 Hz.

## Gamma Ray

Gamma ray wavelengths tend to be less than .01 nm. They've got the highest energy and frequency. Their frequency is typically >10 ^20 Hz. Doctors use gamma rays to image your body. The largest gamma ray generator is the universe.